Facsimile recorder drum



y 4, 1950 P. L. GRAFSTEIN ETAL 2,513,409

FACSIMILE RECORDER DRUM Filed 000. 21, 1947 I INVENTOR. L. G/PAESTEIA)1} A. COOLEy 'IIIIIIII/IIIIIIIIlIIlIIIIIIII/9 BY 2M ATTORNEY PaientedJuly 4, 1950 UNITED] STATES PATENT OFFICE EACSIMILE. RECORDER DRUMApplicationpctoher 21, 1947, Serial No. 781,090

2 Claims.

This invention relates to a drum or sheet holder for fascimileequipment, and more particularly to clamping devices for holding theedges of a sheet on a drum or other support.

In facsimile equipment used for the copying, transmission or recordingof pictures and messages, a revolving drum driven at synchronous speedis often employed in both the transmitter and recorder for supportingthe copy and the recording sheet, respectively. in the transmitter it isimportant to hold the picture or. message copy securely on the drumandclosely in contact with the surface of the drum. The sheet should heheld in such a manerthat it does not either slip or bulge so that it-isout of focus with the transmitting optical system. Similarly, on therecording equipment, the recording film or paper must be held securelyand tightly against the surface of the supporting drum. In addition, itis important that the sheet-holding means be easy to adjust or operate.

Where a clampbar is used on a recording drum employed for electriccurrent recording, the clamp bar must lie flush with the surface of thedrum and be quite thin at its leading edge so that the recording styluscan ride freely over the clamp bar without undue bouncing and Withoutinjur ing the stylus. This was so difficult of accomplishment that formany years other clamping means, such as spring bands encirclingthe-drum, have been used for stylus recording equipment although muchless satisfactory from the standpoint of security or holdingeffectiveness and ease of operation.

In general terms, itis the object of the invention to provide clampingmeans for a facsimile drum or the like which is more satisfactory andsimpler to use than prior devices and which may be used in a transceiveror recorder employing a direct-recording stylus riding over therecording sheet.

For transmitters or photographic recorders,

drum clamp bars extending along the length" of the drum have beenproposed which can be raised or tilted on either edge or which usedseparate clamps to clamp both ends of the sheet or the film to besecured to the drum. Since it is necessary to hold one edge of the sheetsecurely while the clamp bar is raised to facilitate the in sertion andclamping of the other edge, these prior devices possessed certaindrawbacks from a practical standpoint. Either they did not open up wideenough to permit easy insertion of the sheet or they protruded above thesurface of the drum and thereforecould not be used for stylus recordingmachines. Where separate clamping means was provided for-each end of thesheet, the width of the sheet holder reduced: the usable area 'of thedrum 'to an undesirable extent.

Another object of the present invention is to overcome thesedisadvantagesand provide a flush clamping bar of minimum width which iseffective to hold either edgeof the sheet securely when the clampisopened for insertion of the other edge. This is particularly importantin the case of the larger sizes of drums where, after preliminary.mounting of the sheet, it is sometimes necessary to open up one or bothsides of the paper clamp while pulling. the sheet tight 'to eliminatewrinkles and bulges.

Another object of the invention is to provide a tilting clamp bar orsheet-holding element of the character described which is easier tooperate than those used heretofore and which includes improved detentmeans to hold the same in the tilted or open position, releasing thehands for usein grasping the sheet or the controls of the machine.

Other objects and advantages of the invention will appear from thefollowing detailed description of the preferred modification shown inthe accompanying drawings. In the drawings:

Fig. 1 is a top plan view of a' facsimile recorder embodying theinvention.

Fig. 2 is a longitudinal sectional View to an en larged scale throughthe drum clamp bar shown in Fig. 1.

Fig. 3 is a cross-sectional view taken on the line III- 1H of Fig. 1.

Figs. 4 and 5 are detail views to an enlarged scale of the drum clampand its supporting structure, and

Fig. 6 is a detail view of the stylus holder.

Referring to Figs. 1 and 3, a facsimile recorder is shown embodying .aconventional arrangement of motor Iii, clutch H and supporting frame 12for a rotating drum or cylindrical sheet holder I3. By way of example,the recorder is shown as provided with a recording stylus it carried bya stylusholder l 5 which is actuated by a lead screw l6, whereby thestylus H5 is caused to traverse the length of the drum [3 as therecording sheet revolves on said drum. The threaded halfnut member I! ispivoted on the holder l5 so that it can be manually disengaged from thelead screw [5. The sheet holder embodying the invention may also be usedin connection with other facsimile recording or transmitting machinesor, in fact, with any machines or apparatus wherein a sheet has to besupported substantially in the same manner. However, it will be apparentthat the use of the recording stylus M requires clamping means which issubstantially flush with the drum so that the stylus will ride over theclamp bar and be maintained uniformly in contact with the sheet duringsubstantially the entire rotation of the drum.

In accordance with the present invention, the recording sheet issecurely mounted on the drum by clamping the same under the oppositeedges of a thin elongated clamp bar 2| which extends the entire lengthof the drum l3 and which lies in a recess in the outer surface thereof,asshown.

The clamp bar 2| is preferably made of strong elastic metal such assteel, Phosphor bronze or beryllium copper, but may be so thin that itis not stiff enough without reinforcement to retain its straightnessalong the linear drum surface, particularly in the case of a long drum.To provide the necessary stillness and to enable the clamp bar 2| to betilted for loading the drum, reinforcing means is provided in the formof a U-shaped channel bar 22 positioned parallel and inspaced'relation'to the clamp bar 2|, as shown in Figs. 2 and 4. Theoperating and reinforcing bar 22, in the preferred form of theinvention, is secured to the clamp bar 2| by a plurality of posts 23.The posts 23 are riveted or secured in any other desired manner to'theclamp bar 2|, and project through clearance holes or apertures in thedrum and said bar 22'. Each of said posts is provided at the inner endwith a head 24, and a compression spring 25 is disposed between the head'24 and the channel bar 22. If desired, the head 24 may be adjustablefor obtaining the proper tension in the coiled spring 25, as for exampleby threading the end of the post 23.

The channel bar 22 is required on a relatively long dr'um,'ten inches ormore in length. On a short drum, the bar may be omitted. In this case,short sections of channel or the like may serve as spring seats on theposts 23, between the ends of the springs 25 and the brackets 21.

As shown more clearly in Figs. 2 and 4, one or more angular slottedbrackets 2! forming an inwardly projecting shoulder are provided,preferably one at each end of the drum. The posts 23 project through thebrackets 27 whereby the channel bar 22 and the clamp bar 2| are guidedby the slots in said bracket and thus held against longitudinaldisplacement on the drum. The location and configuration of the brackets27 are such that the spring 25 surrounding each post 23 is compressedwhen the posts are pushed from the normal central position, so that theclamp bar 2| is normally held firmly in the position shown in full linesin Fig. 4.

In mounting a sheet on the drum l3, the clamp bar 2| is pivoted ortilted to the position shown in dotted lines in Fig. 4, to permitinsertion of the edge of the sheet underneath the bar. This is done byrocking or pushing the reinforcing bar 22 to one side of its centralnormal position. As shown, the bar '22 projects through a slot 23 in oneor both of the end bells of the drum l3 (see Figs. 2 and 3). A handle orthumb-piece 33 may be provided on the end of the bar 22 for raising theclamp bar 2 l The brackets 2'! are preferably formed with cammingsurfaces including angular shoulders or corners 3| constituting, incombination with the abutting portion of the bar 22 and spring 25,simple detent means for holding the clamp bar 2| in its central clampingposition or in either of its tilted positions, one of which is shown indottedlines in Fig. 4.

In accordance with a further feature of the invention, the clamp bar 2|is provided at each end with an apertured ofiset portion or member 33,shown more clearly in Fig. 5. A projecting lug 34 extends through theaperture in the member 33, the lug 34 at each end of the drum l3 beingfixed to or integral with the drum. With this construction it will beapparent that as the posts 23 are tilted, the clamp bar 2| is tiltedabout one of the edges of the lug 34. Since the edges of the lug 34which form pivots for the clamp bar 2| are substantially in alignmentwith the edges of the clamp bar which press against the sheet mountedonthe drum, the sheet is held firmly at one end by the lower edge of thebar when it is tilted to raise the opposite edge of the bar. Theaperture in the offset portion 33 of the clamp bar preferably is shapedto hold the clamp bar against one edge of the lug 34 as the oppositeedge of the clamp bar is raised. While the lug 34 constrains themovement of the clamp bar 2| at its extreme :endsduring the loadingoperation, the lower edge of; the tilted bar is also held in contactwith the sheet along its entire length on account of the resilient means25 acting on the bar along its length and tending to press the baragainst the drum.

Fig. 6 illustrates a preferred form of stylus holder i5. As shown, thestylus l4 in the form of a, thin wire or needle, is attached to theouter offset lug or ear 35 of a steel armature which is pivotallymounted on a small horse-shoe magnet 36. The line 31 represents the lineof contact between the stylus ill and the recording sheet, and it willbe noted that the engagement of the point of the stylus with the sheetholds the rear free end of the armature from abutting against the magnet36. Thus the stylus is held yieldingly in engagement with the sheet bythe magnetic attraction of the armature 35, and wear of the stylus istaken up by the pivoted movement of the armature in relation to the polefaces of the magnet 36. To replace the stylus, the armature with itsattached stylus point I4 is simply pulled off the magnet 36 and anotherarmature and point slipped in place. No claims are made in the presentapplication to this feature, which is disclosed and claimed in theco-pending application of A. G. Cooley, Ser. No. 787,779, filed November24, 1947.

It will be apparent that the invention provide an improved clampingmeans for a drum or other sheet holder which is simple in construction,easy to operate and usable With a direct recording system employing astylus riding on a sheet.

While a preferred. form of the invention has been described in detailfor the purpose of explaining the underlying principles thereof, variouschanges and modifications can be made without departing from the scopeof the invention as defined in the appended claims.

We claim:

1. In facsimile apparatus of the character described, a rotatable drum,a clamp bar thereon having offset portions at the ends of the drum,means forming a dual pivotal support for the offset portions of theclamp bar to enable tilting of the bar about an axis along eitherlongitudinal edge thereof, a plurality of inwardly projecting members onsaid clamp bar and means to actuate said projecting members to causetilting of the clamp bar to raise its edge above the drum for insertionof the sheet to be mounted on the drum.

2. A clamp bar for a drum or similar sheet 5 6 holder comprisinginwardly projecting posts, a. clamp bar to its normal flat position tohold the coiled spring on the inner end of each post, deedge of a sheetagainst the surface of the drum. tent means including said springs andangular PAUL GRAFSTEIN- brackets on said drum adjacent the respectiveAUSTIN COOLEY- posts, said detent means being arranged to hold 5 theclamp bar either fiat on the surface of the REFERENCES CITED drum orWith one edge of the bar raised above The following references are ofrecord in the the surface of the drum, and means including a file ofthis patent:

U-shaped channel bar engaging at least one of UNITED STATES PATENTS theposts adapted for manual actuation to raise 10 Number Name Date on ofthe clam b r nd t t e the e edge p a 0 res or 2,372,774 Finch Apr. 3,1945

